There are a number of ways to do this in Photoshop, but MakeUseOf opts to use the very handy Render > Clouds tool (Under Filter), which creates a cloud-like pattern using your currently chosen ...

Photoshop tutorial showing how to write cloud text in the sky creating the look of words written by sky-writing jets. If the "Clouds" pattern is missing... 1) Go to "Window" 2) "Patterns" 3) Click the ...